Wireless communication systems such as mobile phone systems and wireless local area networks (LANs) are widely used today. Some wireless communication devices are capable of using different types of wireless communication networks. For example, mobile phones are available that include two wireless communication units: one that connects to a mobile communication network to perform wireless communication and the other that connects to a wireless LAN to perform wireless communication. Such a wireless communication device allows a user to select a wireless communication network to use according to the location where the user is. Thus, the user may benefit from the advantages of different types of wireless communication networks. For example, in a place where a wireless LAN is available, the user may use the wireless LAN and use a mobile communication network in other places to benefit from advantages of the former, such as high speed communication, and from advantages of the latter, such as a wide communication area.
A mobile phone has been proposed that includes a mobile phone communication unit and a wireless LAN communication unit which are initialized to be placed in a standby mode or a sleep mode when they are powered so that the time requested for starting communication may be reduced (Japanese Laid-Open Patent Publication No. 2008-263520). A terminal device has been proposed that determines, on the basis of a power conservation parameter set at an access point, whether the terminal device is operating in a power saving mode or a non-power saving mode, and displays the determined mode on a display (Japanese Laid-Open Patent Publication No. 2009-118160).
Some wireless communication networks dynamically allocate an Internet Protocol (IP) address to a wireless communication device and, after no communication has been performed for a predetermined period of time, deallocate the IP address.
The wireless communication device may use a service in which the wireless communication device is informed about the presence of a message directed to the wireless communication device by the wireless communication network (a so-called push service) while the wireless communication device has an IP address allocated to it. Therefore the wireless communication device may operate so as to maintain the allocated IP address (for example communicates with the wireless communication network at regular intervals) even in a standby mode. However, there is the problem of how to cause the multiple wireless communication units of a wireless communication device that may use different types of wireless communication networks to operate so that power consumption may be effectively saved.